Double-cutting band-saw.



' El E. THOMAS.

uouBLa'cuTrma ANn'sAw.

(Application Sled Oct. 12, 1901.)

(No Model.)

TH: Nonms PETERS cva. Pnorau'mo.. wAsNws-mn. u, c.

i EDWIN E. THOMAS, OF ST. PAUL, MINNESOTA, ASSIGNOR OFONE-HALF TO.V

UNION IRON WORKS, OF MINNEAPOLIS, MINNESOTA, A CORPORATION UNITED[STATES OF MINNESOTA.

PATENT OEEICE.

DOUBLE-CUTTING BAND-SAW.

SPECIFICATION forming part of Letters` Patent No.`690,678, dated January7,1902.

Application' filed October 12 1901. Serial No. 78,411. (No model.)

To all whom, t may concern.:

Be it known that LEDWINE. THOMAS, of St. Paul, Ramsey county, Minnesota,have invented certain new and useful Improvements in Double-CuttingBand-Saws, of which the following is a specification.

In the operation of a band-mill it is necessary that the edges of thesaw be under'considerable tension to i-nsure good results in sawing, andto produce this tension it is customary to lengthen out the saw alongits middle line, so that when placed onthe Wheels its middle portionwill be out of contact with them and the strain will be thrown out tothe edges, which will sustain the tension of the saw.I This lengtheningor expanding of the middle portion of the saw is done by hammering orrolling the metal and is a tedious and laborious task and one lthatrequires the services of skilled workmen to insure uniform stretching orexpansion.

The object, therefore, of my invention is to provide a double-cuttingband-saw of such construction that the operation of expanding its middleportion will be greatly simplified and facilitated.

A further object is to provide a saw that can be more readily fitted towheels having crowning faces.'

The invention consists generally in providinga band-saw with a series oflongitudinal slots arranged at intervals along its middle line.

Further, the invention consists in various constructions andcombinations, all as hereinafter described, and particularly pointed outin the claims.

In the accompanying drawings,formin g part of this specification, Figurel is a plan View of a portion of a double-cutting band-saw emgwhich'connect theopposite edges of the saw.

These slots cause a considerable reduction in the amount of metalalongthe center of the saw without materially weakening it and reduce,verylargely the area that the workmen have to hammer or roll to properlyexpand the saw.

Instead of going over the whole middle portion of the saw, asheretofore, it is only necessary to hammer the edges of the slots alittle to produce the requisite expansion, and this operation does notrequire nearly as much care and attention as has been necessary toexercise in expanding the ordinary band-saw.

To adapt the same for use on crown-faced wheels, the bridges are strucka fewy strokes with a hammer to bend them sufficiently to clear thehighest point of the crown and cause the weight applied on the wheels tobe sustained by the edges of the saw.

'I may provide a single cutting band-saw with longitudinal. slots forthe same purpose; but the invention is designed and I regard it asparticularly adapted for use with saws of the double-cutting type.

I claim as my invention- Y '1. A band-saw -provided with a series ofelongated slots extending lengthwise thereof at intervals.

2. A double cutting band saw provided with a series of comparativelylong narrow slots extending lengthwise thereof along its medial line.

EDWIN E. THOMAS.

In presence of RICHARD PAUL, M. C. NooNAN.

